Reversible changes in the nucleosomal organization of a human H4 histone gene during the cell cycle

Abstract

The organization of nucleosomes associated with a cell cycle regulated human H4 histone gene was examined in synchronized HeLa S3 cells. At various times during the cell cycle, nuclei were digested with micrococcal nuclease, and the nucleosomal pattern of the gene was obtained by Southern blot analysis using radiolabeled human histone H4 gene probes. We have detected reversible changes during the cell cycle in the chromatin structure of this gene, as reflected by the shortening of the nucleosomal spacing after replication and the peak of transcription. This variation is also observed when DNA and protein syntheses are inhibited. By using a probe that comprises 250 base pairs (bp) of the coding region and 240 bp of the 5' end of the gene, containing the promoter and DNase I sensitive sequences, we also have observed a general disruption of the nucleosomal organization, which is reflected by a degeneration of the characteristic nucleosomal ladder produced by micrococcal nuclease digestion. This modification coincides with the replication and active transcription of the gene (early S phase), which recovers its regular nucleosomal appearance when both processes have been completed, although the nucleosome linker length is shortened. When the probe utilized comprises the distal 3' end of the gene, there is no disruption of the nucleosomal pattern, but the linker region also exhibits a shortened length. A non-cell cycle regulated gene (beta-globin) does not exhibit such modifications in any of the situations analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Nuclear architecture supports integration of physiological regulatory signals for transcription of cell growth and tissue‐specific genes during osteoblast differentiation

“…The presence of nucleosomes in the human H4 histone gene promoter [Chrysogelos et al, 1985Moreno et al, 1986;Pauli et al, 19891 provides the possibility for increasing the proximity of independent regulatory elements that support synergistic and/or antagonistic cooperative interactions between histone gene DNA binding activities. Involvement of chromatin structure with transcriptional regulation as related to growth control is consistent with variations in nucleosome organization as a function of cell cycle progression [Moreno et al, 19861.…”

“…This is reflected by accessibility to micrococcal nuclease, DNase I, SI nuclease, and a series of restriction enzymes [Chrysogelos et al, 1985;Moreno et al, 1986;Pauli et al, 19891.…”

Histone gene transcription: A model for responsiveness to an integrated series of regulatory signals mediating cell cycle control and proliferation/differentiation interrelationships

“…7) may serve to increase the proximity of independent regulatory elements, and supports synergistic and/or antagonistic cooperative interactions between histone gene DNA binding activities. In addition, chromatin structure and nucleosomal organization varies as a function of the cell cycle [Moreno et al, 1986;Chrysogelos et al, 19891, which may enhance and restrict accessibility of transcription factors, and modulate the extent to which DNA-bound factors are phosphorylated. The specific mechanisms by which the 5' histone gene promoter regulatory elements and sequence-specific transactivating factors partici- Fig.…”

Maintenance of Open Chromatin and Selective Genomic Occupancy at the Cell Cycle-Regulated Histone H4 Promoter during Differentiation of HL-60 Promyelocytic Leukemia Cells

“…The site II domain is responsible for cell cycle regulation of transcription during S phase, while the enhancer element site I is required for maximal activation of transcription (18,26). Studies using HeLa cells revealed changes in the chromatin structure of the H4/n gene that are functionally related to modulations in transcription during the cell cycle (6,21). However, it remains to be determined whether there is an obligatory reorganization of chromatin structure to silence histone gene transcription in differentiating cells.…”